Production of formamid



Patented Apr. 27, 1926.

UNITED STATES PATENT OFFICE.

REINHOLDFICK, OF LUDWIGSHAFEN-ON-RHINE, GERMANY, ASSIGNOR TO BADISOHE ANILIN- 8c SODA-FABRIK, OF LUDWIGSHAFEN-ON-RHINE, GREMANY, A (103- PORATION OF GERMANY.

PRODUCTION OF FORMAMID.

No Drawing.

To all whom it may -110mm.

Be it known that I, RnINHoLn FICK, a 'citizen of the German Empire, residing at Ludwigshafen-on-Rhine, Germany, have invented new and useful Improvements in Production of Formamid, of whichthe following is a specification.

Formamid though a compound possessing Various valuable uses, can be prepared from ammonium formats, according to the known methods, only with trouble and considerable loss as the conversion takes place slowly and in an incomplete way and with the formation of undesirable by-products.

According to my invention, ammonium form-ate is rapidly and completely transformed into formamid by passing it with a current of ammonia and with or without inert gases, over suitable catalysts. The temperature should be moderately high, e. g. between about 100 degrees and 200degrees centigrade in order to avoid a more farreachmg reaction with a formation of cyanhydric acid taking place in a substantial degree. Catalysts of a dehydrating nature have according to my invention proved suitable as for example bauxite, alumina, titanium oxid, thoria, silica, iron oxid or oxids of other metals or phosphates of aluminium,

china clay, pumice stone, kieselguhr and others. Such bodies are preferably heated to a high temperature prior to use and may be employed either alone or mixed with each other or with supports.

As the production of formamid is efiected in the presence of ammonia, ammonium formate can be replaced by freeformic acid when of course an excess of ammonia must be present, and both ammonium formate Application filed April 8, 1925. Serial No. 20,548.

Without departing from the scope of the in-.

invention.

Example 1.

E mamplc 2.

An aqueous solution of ammonium formate of 60 per cent strength is evaporated in a rapid current of ammonia and the mixture passed through a layer of calcined bauxite kept at about 170 degrees centigrade. The reaction gases are passed through a column the temperature of which is suitably controlled so as to condense only formamid while water vapors are subsequently condensed in a separate cooler. The gaseous ammonia is led back in a cycle, passing, if desired, through a preheater or heat exchanger. Formamid is produced in a nearly theoretical yield and practically free from water. Scarcely any gaseous products of decomposition are produced. The circulating gaseous ammonia may be mixed with other gases, for example air, nitrogen, hydrogen and the like.

When formic acid is en'iployed. instead of ammonium formate the process may be carried out in a similar manner.

I claim I 1. A process for the production of formamid which consists in passing ammonium formats in the vapor phase together with ammonia over a contactmass at a temperature below that at which substantial amounts of cyanhydric acid are formed.

2. A process for the production of formamid w ieh consists in passing ammonium formate in the vapor phase together with ammonia over a contact mass of a dehydrating character at a temperature not surpassing about 200 degrees centigrade.

a 3. A rocess for the production of formamid w ich consists in assing ammonium formate in the vapor p ase together with ammonia and water vapor over a contact mass of a dehydrating character at a temperature not surpassing about 200 degrees centigrade.

4. A process for the production of formamid whlch consists 1n asslng ammonlum .formate in the vapor p ase together with ammonia and anfme'rt gas over a contact mass of a dehydrating character at a temperature not surpassing about 200 degrees centigrade.

5. The rocess of manufacturing formamid wh1c consists in evaporating formic acid m an excess of gaseous ammonia and passing the mixture over a contact mass of a- -ing character at a temperature not surpassing about 200 degrees centigrade and subjccting the reaction gases to fractional cooling so as to condense formamid but leaving water-vapor substantially uncondensed.

In testimony whereofI have hereunto set my hand.

REINHOLD FICK. 

